Engines and their associated parts use lubricants, such as oil, to facilitate the movement of internal components and improve and/or lengthen their respective working lifetimes. These lubricants, along with various additives, possess a number of different lubricating properties, such as properties for reducing soot/sludge formation, corrosion or oxidation, reducing friction, thermal decomposition, extreme pressure and wear, etc. Generally, over the lifetime of a lubricant, additives in the lubricants deplete and/or change form, thus reducing their effectiveness. As a result, over time, lubricants degrade and ultimately must be replaced.
Time release additives for lubricants may be useful to supplement and/or provide additional lubricating properties to lubricant compositions, thereby extending their useful lifetime. Some slow release lubricant additives are known and, for example, may be utilized in oil filters. Such additives may be incorporated into thermoplastic polymers, for example, which slowly dissolve into the oil being processed by the filter. Examples of such additives are disclosed in U.S. Pat. No. 4,075,098, the entirety of which is incorporated herein by reference. Other additives may be incorporated into polymers, which are oil-permeable at elevated engine temperatures. Examples of such additives are disclosed in U.S. Pat. No. 4,066,559, the entirety of which is incorporated herein by reference. Still other additives are incorporated into particles which are oil-insoluble but oil-wettable. Examples of such additives are disclosed in U.S. Pat. No. 5,478,463, the entirety of which is incorporated herein by reference.
In another approach, oil-soluble solid polymers capable of functioning as viscosity improvers are provided inside an oil filter, with or without additional additives being incorporated into the polymer. Examples of such additives are disclosed in U.S. Pat. No. 4,014,794, the entirety of which is incorporated herein by reference. Although these systems are capable of introducing lubricant additives into the oil being filtered, they typically require inert carriers for slow release of the additives into the oil.
In addition, U.S. Pat. No. 7,384,896, the entirety of which is incorporated herein by reference, discloses additive gels that can provide additives to a functional fluid over time. The additive gel comprises i.) at least two additives selected from the group comprising detergents, dispersants, acids, bases, over based detergent, succinated polyolefins or mixtures thereof wherein the selected additives when combined form a gel; ii.) optionally at least one additive comprising viscosity modifier(s), friction modifier(s), detergent(s), cloud point depressant(s), pour point depressant(s), demulsifier(s), flow improver(s), anti static agent(s), dispersant(s), antioxidant(s), antifoam(s), corrosion/rust inhibitor(s), extreme pressure/antiwear agent(s), seal swell agent(s), lubricity aid(s), antimisting agent(s), and mixtures thereof; resulting in a controlled release gel that over time releases at least one desired additive into a functional fluid when the gel is contacted with the functional fluid.
Also, U.S. Pat. No. 7,417,012, the entirety of which is incorporated herein by reference, discloses a lubricant additive gel formed by the gellation of two or more lubricant additives for the slow release of the additive components into a fluid. The lubricant additive gel slowly releases into its component lubricant additives when contacted with the fluid such as an oil thereby serving as a lubricant fluid such as an oil.
U.S. Publication No. 2006/0079413, the entirety of which is incorporated herein by reference, discloses formulations using tartaric compounds in a low sulfur, low ash and low phosphorous lubricant to lower wear, and friction and improve fuel economy.
U.S. Publication No. 2007/0004601, the entirety of which is incorporated herein by reference, discloses a release additive composition including at least one overbased detergent present in a form chosen from a solid and a semi-solid. Also disclosed is a lubrication system and a method of improving the drain interval of oil.
U.S. Publication No. 2007/0004604, the entirety of which is incorporated herein by reference, discloses a release additive composition including at least one dispersant viscosity index improver present in a form chosen from a semi-solid and a solid.
In addition, U.S. Publication No. 2007/0049505, the entirety of which is incorporated herein by reference, discloses a method of lubricating containing: (a) employing a first functional fluid, (b) adding or contacting the first functional fluid with a controlled release gel wherein the controlled release gel has the desired additives to be released imparting the desired properties into the first functional fluid which is for lubricating a mechanical device; and/or adding a delivery system with the desired additives for a second functional fluid; (c) releasing the desired additives from the delivery system into the first functional fluid resulting in the first functional fluid changing into a second functional fluid, with the proviso that the second functional fluid is different from the first functional fluid.
U.S. Publication No. 2008/0015126, the entirety of which is incorporated herein by reference, discloses a control release gel for delivery of additives free of producing ash to substantially free of producing ash into a lubricant.
Finally, U.S. Publication No. 2008/0108531, the entirety of which is incorporated herein by reference, discloses the use of viscosity modifiers in a control release additive gel containing a viscosity modifier that control releases additives into a lubricant.
Even in view of the above-described lubricant additives, the need remains for effective additives, e.g., effective friction modifier additives, that can be released, optionally controllably released, into a lubricant to replenish and/or enhance the lubricating properties of the lubricant that otherwise may be reduced over time.